Propagation of plants



retested Sept. s, 1938 UNITED STATES PATENT OFFICE 2,129,599 vPROPAGATION or PLANTS Percy W.

Yonkers, N. Y

Zimmerman and Albert E. Hitchcock, assignors, to Boyce Thompson NoDrawing. Application March 17, 1937, Serial No. 131,368

10 Claims.

This invention relates to the propagation of plants from cuttings, andhas for its object the provision of an improved method for inducingroot-growth on such cuttings. This application is a continuation in partof our copending application Serial No. 72,058, filed April 1, 1936.

It has heretofore been recognized that certain gases (e. g. ethylene)induce definite types of formative responses on plants, such asstimulation or retardation of the growth of certain tissues, and theinitiation of cell division which results in various kinds ofproliferations or in the formation of roots. As a result of anexhaustive investigation of the effects of various types of growthsubstances on plants, we have discovered that certain organic compoundsexercise a pronounced stimulating effect on root-growth, and are highlyvaluable in promoting and inducing root-growth on plant slips orcuttings. In this specification and in the appended claims, the wordcutting and the expression cuttings and the like are used generically todesignate any part of a plant, including buds, scions, and slips,

' used for purposes of propagation, and the invention advantageously maybe employed to promote plant propagation from any such plant part byinducing active callus formation, root-growth, and similar plantphysiological responses.

Among the organic compounds which we find useful for inducingroot-growth are Indolebutyric acid and its derivatives. In the appendedclaims these compounds are dglned generically as indole substitutionproducts f a compound having the butyric acid structure as its nucleus,that is, the butyric acid structure (which does not include the acidhydrogen atom of butyric acid itself) is the base or foundation of themolecule of the compound.

Based on the foregoing discovery, our present invention involves theimprovement in propagating plants from cuttings which comprises the stepof inducing root-growth by subjecting the cutting to the action of asubstance of the group consisting of indolebutyric acid and itsderivatives.

Only a minute amount of the substance is necessary to induce vigorousroot-growth and high concentrations are usually injurious rather thanbeneficial. I

Indolebutyric acid itself is an especially satisfactory substance foruse in the practice of our invention, but derivatives of indolebutyricacid in general may be employed with success. Among the derivatives ofindolebutyric acid which we have found of special advantage in thepractice of the invention are salts of indolebutyric acid and esters ofindolebutyric acid. The alkali metal salts (including the ammonium salt)and the alkali-earth metal salts of indolebutyric acid in general arethe preferred salts for use in carrying out the invention. The loweralcohol esters (such as the methyl and ethyl esters) of indolebutyric'acid constitute the preferred esters for use in carrying out theinvention. So far as we have now determined, however, all of the saltsand esters of indolebutyric acid possess definite powers of inducingroot-growth and similar plant physiological responses on cuttings andthe like.

Treatment of the more succulent type of plants, such as the tomato,African marigold, tobacco, etc, with the growth substances of thepresent invention (i. e. indolebutyric acid and its derivatives) hasshown that roots may be induced to grow from any portion of the stem,and even from the leaves of many species. The growth substance may bemixed with lanolin, olive oil, paraffin oil, maize oil, castor oil,Amalie oil (a commercial mineral oil) and the like, and a thin film ofthe mixture may be applied by rubbing with a glass rod on the epidermisof the region to be treated. The usual concentrations found mosteffective are from about 0.01 to 2% of the growth substance on theweight of lanolin or the like. Lanolin and similar preparations of thegrowth substance may be applied directly to the cutting, or they may beplaced on shoots which remain attached to the parent plant during theperiod of treatment and are then removed and made into cuttings that arehandled at this stage the same as is normally done in commercialpractice. When applied to "the stems, the growth substances of thepresent invention definitely cause local initiation of roots on growingplants of tomato, sun

flower, marigold, artichoke, buckwheat, dahlia. and tobacco. If theplants are kept in a glass case after treatment, the new roots forcetheir way through the epidermis and out into the humid atmosphere. Thetime required for roots to make their appearance varies with the growthsubstance used, the concentration, the species of plants, and the exactplace on the plant where the material is applied.

Indolebutyric acid itself is especially effective for initiating rootson both stems and leaves.

In the case of indolebutyric acid itself, a 0.01

to 2.0% solution in lanolin causes negative (away from side wheresubstance was applied) bending of tomato stems. Positive (toward sidewhere substance is applied) bending occurs when the concentration of thesubstance is high enough to injure the tissue or retard the normal rateof growth. A 0.1 to 2.0% solution of indolebutyric acid in general isoptimum for inducing adventitious roots.

In general, it might be stated that the most eflective concentration forroot initiation falls just below that causing positive bending of thestem, or at the point where there is slight retardation of growth. whenthe concentration is high enough to cause evident injury, roots appearon the opposite side or adjoining the place on the stem where thesubstance is applied. This result indicates that as the growth substancediffuses away from the point of toxic concentration a range is reachedwhich is eifective for inducing roots. Under favorable conditions, 5 to10 mg. of indolebutyric acid per gram of lanolin causes roots to beinduced and appear through the epidermis on tomato in six days, marigoldin five days, tobacco in eight days, and artichoke in six days. Onemilligram of indolebutyric acid per gram of lanolin is effective, butusually requires two days more to induce roots.

In commercial practice, treatment of the cutting or parent plant with awater solution of the growth substance is generally more satisfactoryand applicable than treatment with lanolin (and similar) preparations.Thus, the growth substance may be dissolved in the water (in which it isonly sparingly soluble), and the basal end of the plant cutting placedin the solution. The

basal end of the cutting immersed in such a solu tion for from severalhours to several days induces subsequent growth of excellent rootsystems. The concentration of the growth substance in the aqueoussolution is relatively minute, say a few milligrams per cc. of water.Thus, solutions containing 05mg. to 10 mg. of indolebutyric acid per 100cc. of water give satisfactory results for many species.

In practicing the invention with water solutions of the growthsubstances, the plant cutting is placed in the solution for a period oftime rang ing from a few hours to several days. The cutting, aftertreatment in the solution, may be planted in a mixture of half sand andhalf peat moss, for example, or in soil. The efiectiveness of thetreatment is indicated in many ways, such as the increased percentage ofrooted cuttings, increase in size of the root systems, earlierappearance of roots, greater total number of roots, and the emergence ofroots from stem tissue above the base of the cutting as well as at thebase.

Cuttings of the American holly (Ilea: opaca) placed in solutions ofindolebutyric acid (1 to 4 mg. per 100 cc.) for periods ranging fromeight hours to two days produced excellent root systems six to ten weeksafter treatment and plant ing. These results are of special significancesince cuttings of American holly are difiicult to root. A similarfavorable-response to treatment with water solutions of indolebutyricacid was obtained with Japanese maple at the end of six to ten weeks,Japanese holly (Ilea: crenata) at the end of about four weeks, Taxus atthe end of eight to ten weeks, American elm at the end of four to sixweeks, and with many other genera and species at the end of periodsranging from two to ten weeks.

By the term "indolebutyric acid as used herein and in the appendedclaims we refer specifically to beta-indolebutyric acid(gamma-[indolyl-(3) l-butyric acid) having the structural formulaCHICHaCIIiCOOH The derivatives of indolebutyric acid referred to hereinand in the appended claims are those compounds in which an atom otherthan a hydrogen atom or a radical is substituted for the acid hydrogenatom of the indolebutyric acid particularly identified above.

We claim:

1. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of an indole substitution product of a compoundhaving butyric acid structure as its nucleus.

2. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of indolebutyric acid.

3. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of an alkali metal salt of indolebutyric acid.

4. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of a lower alcohol ester of indolebutyric acid.

5. The improvement in propagating plants from cuttings and thelike whichcomprises the step of inducing root-growth by subjecting the basal endof the cutting to the action of a substance of the group consisting ofindolebutyric acid, salts of indolebutyric acid, and esters ofindolebutyric acid.

6. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting'to the action of indolebutyric acid.

'7. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of an alkali metal'salt ofindolebutyric acid.

8. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of a .lower alcohol ester ofindolebutyric acid.

9. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by immersion treatmentof the basal end of the cutting in an aqueous solution containingindolebutyric acid.

10. The improvement in propagating plants from cuttings and the likewhich comprises the stepof inducing root-growth by immersion treatmentof the basal end of the cutting in an aqueous solution containing analkali metal salt of indolebutyric acid.

PERCY W. ZIMMERMAN. ALBERT E. HITCHCOCK.

Patent No'. 2,129,599.

7 CERTIFICATE OF CORRECTION.

September 6', 1958. PERCY w. ZIIII'IEBMAN, ET AL. F

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second colmpn, line 21,. claim-l, after. "having" insert the word the;and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 11th day of October, A. D. 19

Henry Van Arsdale 7 Acting Conmissioner of Patents.

